There is a lot of what-if here, but the reality is that most people in the USA prefer the flexibility and speed of (1) Driving wherever and whenever and carrying all your stuff with you, and then (2) flying to your destination for speed. You can cross the east coast in 3 hours or the go to the west cost in 6 on a convenient red-eye.
Taking the train is more a novelty, and unclear who would actually use it regularly because it takes much longer (10 hours east cost, 20 hours coast to coast), transport on either endpoint requires you to park or taxi, and you lose all flexibility.
We like the idea of the train more than the reality of the train. I've lived in various places around the world where you had to take mass transit always, and all it does is add one to two hours to your commute when I would have much preferred to drive.
Taking the train is more a novelty, and unclear who would actually use it regularly because it takes much longer (10 hours east cost, 20 hours coast to coast), transport on either endpoint requires you to park or taxi, and you lose all flexibility.
We like the idea of the train more than the reality of the train. I've lived in various places around the world where you had to take mass transit always, and all it does is add one to two hours to your commute when I would have much preferred to drive.